Variable condenser



April 25, 1933.

c. E, PARCELL VARIABLE CONDENSER 2 Sheets-Sheet 1 Filed Feb. 13, 1950 y z; y

Inventor C/JQZZ WJZ By 6 57% Q I A ttomey April 25, 1933. 5 PAR 1,905,601

VARIABLE CONDENSER Filed Feb. 15, 1930 2 Sheets-Sheet 2 /6 /7 V \Y I, l

1 2' Inventor [Zap-1 3E a ce/ Attorney Patented Apr. 25, 1933 PATENT" OFFICE cums a. r ncunn, or vm'ron, IOWA vmunnn cormmwsmt Application filed February 18, 1930. Serial No. 428,104.

The present invention relates to variable condensers adapted for use in wireless and radio receiving apparatus and has for its principal object to provide a device of this character capable of a wide range of adjustment.

A further object is to provide a device of this character which-is simple and practical in construction, efficient and reliable in performance, relatively inexpensive to manufacture and install in operative position and which is suitable for use in a. multiple connection to accommodate the multiple stage receivers of the present type of radio receiv- 1 ing sets.

Other objects and advantages reside in the special construction, combination and arrangement of the various elements forming the invention as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming part hereof, wherein like numerals refer to lik parts throughout, and in which:

Figure 1 is a side elevational view of one of the condensers constructed in accordance with my invention,

Figure 2 is a vertical transverse sectional view taken substantially on a line 2-2 of Fi ure 1,

igure 3 is a view in elevation showing the manner of connecting the condensers in series upon a single operating shaft,

Figure 4 is a'sectional view through \the shaft taken on a line 4-4 of Figure 3, and

Figure 5 is a fragmentary front elevational view of the panel associated with the condenser. Referring now to the drawings in detail wherein for the urpose of illustration I have disclosed a pre erred embodiment of the invention, the numeral 5 designates generally the mounting for the condenser which comprises a pair of spaced end plates 6 connected by a plurality of spacing members 7 of insulation material. The end plates 6 are rovided with threaded openings through w ich a spirally threaded screw 8 is threadedly inserted.

Upon the screw 8, between the end plates 6, is mounted a spiral condenser blade 9 havmg its center portion secured within the spira groove 10 of the screw 8. An outer spiral condenser blade 11 is also positioned between the end plates 6 with the outer peripheral edges of the blade secured in spaced grooves 12 formed in the inner edges of the spacing members 7 and having its central portion provided with an enlarged opening 13 to permit the free longitudinal movement of the screw 8.

The sections of the inner and outer spiral blades are shaped substantially uniformly and mounted within respect to each other so that upon the operation of the screw 8, the sections of the inner spiral blade 9 will pass between the sections of the outer spiral blade 11 without coming into contact therewith. It will thus be apparent that the blades composing the condenser may be adjusted with respect to each other fortuning purposes in a manner well known in the art.

In the disclosure illustrated in Figure 1 of the drawings, the screw shaft 8 is provided with an operating knob 14 for adjusting purposes and in the form of the invention illustrated in Figures 3 to 5 inclusive the invention is shown in a gang assembly to provide for uniform adjustment by means of a single control knob 15 which is mounted on the end of a shaft 16 journalled in the panel 17 of the radio set.

The inner end of the shaft 16 is provided with a beveled gear 18 engaging a similar gear 19 formed on one end of a collar 20 mounted on the screw shaft 21. In this form of the invention, the shaft is provided with a longitudinally extending groove 22 for receiving a key 23 carried by the collar 20. It will thus be apparent that the screw will travel through the collar during the adjust- V ment of the condensers. Any suitable means are provided for holding the collar against longitudinal movement.

A drum 23 is also keyed to the shaft 21 for rotation therewith and is provided on its outer periphery with a spirally formed scale 24 regisfering with a window 25 formed in the ane p The convolutions of the scale 24 correspond to the convolutions carried by the inner s iral blade 9 so that the exact position of sad blade with res t to its associated spiral blades will be in icated by the position of the scale with respect to the window.

It is obvious that my invention is susceptible to various changes and modifications in construction without departing from thespirit of the invention or the scope of the afipended claim, and I accordingly claim a such 10 forms of the device to which I am entitled.

Having thus described my invention, what I claim as new is:

A variable condenser com rising a suppgrting plate, a pair of spacefparal el memrs supported from each end portion of said plate, an elongated screw shaft passing through the two pairs of parallel members, some of said members having openings therein engaging the threads of the shaft whereby the shaft will have longitudinal movement in said parallel members, a pair ofspiral blades having their inner peri heries fastened in ortions of the grooves ormcd by the threa of the shaft and each blade being located between one pair of parallel members, bars of non-conducting material connecting the parallel members of each pair together and spaced apart and having rooves 1n their inner edges, a second spira blade located between each pair ofparallel members and having portions of its outer periphery located in and fastened in the grooves of the non-conducting bars, said second blade having an opening at its center through which the shaft and portions of the first blade pass, with the first blade out of contact with the second blade, means located between the Pairs of parallel members for rotating the I sha t without interfering with its longitudi- 4 ml movement, a drum carried by the shaft for movement therewith and located between the pairs of parallel members and a spiral scale carried by the periphery of the drum, the convolutions of the scale corresponding to 4 the convolutions of the spiral blades on the shaft, said supporting plate havin a window therein for exposing portions 0 the scale, with the operating means for the shaft extending through said su porting plate. In testimonywhereof aflix my si ature.

CHARLES E. PAR L 

